Nile tilapia (Oreochromis
niloticus) is a species of fish native to Africa and the
Middle East, and it has become one of the top species used in
aquaculture worldwide. As a result of their extensive use in
aquaculture, the species has been introduced into nonnative
environments following the release or escape from fish
farms. Research efforts conducted collaboratively by the
Museum of Natural Science and The University of Southern
Mississippi - Gulf Coast Research Laboratory have documented the
recent establishment of Nile tilapia in coastal watersheds of
southeastern Mississippi, and researchers consider the species to
pose a significant threat to native fishes and fisheries if their
populations continue to expand.

This species appears not to compete directly for food
resources with native co-occurring sunfishes (e.g., bass,
bream). Nile tilapia feed mainly on bottom sediments (i.e.,
base of the food web) and extract energy from accompanying
organisms in the sediments. However, feeding at the base of
the food web may indirectly force a cascading effect by altering
food types and abundance at upper food web levels commonly foraged
on by fishes such as bass and bream.

Nile tilapia become reproductively mature at a small size
and individuals experience a fast growth rate. In addition,
female Nile tilapia brood eggs, embryo and young in their
mouths. This parental care assures that the majority of their
eggs will survive to the juvenile stage. This strategy coupled
with the fact that females may spawn multiple broods throughout
their extended reproductive season may give this introduced species
a competitive advantage over native fishes and allow them the
capacity to proliferate in nonnative environments.

These adaptations make tilapiine fishes excellent
aquaculture species, but also are the same attributes that allow
them the ability to invade and become established in nonnative
environments. Tilapiine fishes were erroneously considered
incapable of tolerating the cooler water of wintertime Mississippi,
in part justifying their use as an aquaculture species. Like
other cichlid species, however, tilapiine fishes are highly
tolerant to environmental stressors, and temperature tolerance has
been reduced in more saline waters as is typical of coastal
Mississippi.

Efforts should be consider by resource managers to
evaluate the use of tilapia in an aquaculture setting in coastal
watersheds as natural disasters like flooding and hurricanes can
cause tilapias to enter and disperse into other habitats and
drainages thus expanding the invasion. The establishment of exotic
species is a leading threat to native ecosystems, with aquatic
ecosystems at the highest risk. The ability to control exotic
species is often hindered by reacting to negative impacts that
occur during or after establishment.